A method for determining the absolute configuration of a chiral compound that has been used in the past is to subject a combination (such as a complex) of a chiral compound and a specific compound to circular dichroic (CD) spectrophotometric analysis, and determine the absolute configuration of the chiral compound by utilizing the correlation between the Cotton effect sign and the absolute configuration of the chiral compound.
For instance, X. Huang et al. have reported that there is a correlation between the Cotton effect sign and the absolute configuration of a chiral compound, and that circular dichroism is induced by the coordination of a chiral compound to a porphyrin dimer that has been crosslinked with a long crosslinking chain (X. Huang, B. H. Rickmann, B. Borhan, N. Berova, K. Nakanishi, “Zinc Porphyrin Tweezer in Host-Guest Complexation: Determination of Absolute Configurations of Diamines, Amino Acids, and Amino Alcohols by Circular Dichroism,” J. Am. Chem. Soc., 1998, Vol. 120, pp. 6185-6186).
However, this system can only be applied to chiral compounds having two functional groups, such as a diamine or an amino alcohol, because circular dichroism is only induced by the simultaneous coordination of one molecule of chiral compound to two porphyrin units.
Also, M. Takeuchi et al. have reported that a porphyrin dimer having a phenylboronic acid unit exhibits circular dichroism in the presence of various kinds of sugar (M. Takeuchi, T. Imada, S. Shinkai, “Molecular Design of Highly Selective and Sensitive Sugar Tweezers from Boronic-Acid-Appended μ-Oxo-bis[porphinatoiron (III)]s,” Bull. Chem. Soc. Jpn., 1998, Vol. 71, 1117-1123).
This system can only be applied to sugars that form bonds with boronic acid. Furthermore, it is impossible to determine the absolute configuration of one specific asymmetric center out of the many asymmetric centers had by a sugar.
Thus, no method has been reported for determining absolute configuration which could be applied to a wide variety of chiral compounds.
In view of this, the inventors researched methods for determining the absolute configuration of a chiral compound with which the absolute configuration of many different chiral compounds could be determined precisely and easily. It has been discovered in recent years that when a chiral compound is coordinated to a metal porphyrin dimer which is a metal porphyrin dimer and in which both porphyrin rings include zinc, iron, manganese, or ruthenium as their metal center, circular dichroism is induced and there is a correlation between the Cotton effect sign and the absolute configuration of the chiral compound, and this has led to the completion of a novel method for determining the absolute configuration of a chiral compound (Japanese Unexamined Patent Publication 2001-220392).
Nevertheless, a problem with this method is that when the chiral compound is an amino alcohol or a diamine, the Cotton effect sign may be change with the concentration in which the chiral compound is contained in the sample solution.